1. Field of the Invention
The present invention relates to an image reading apparatus that reads a light transmissive portion of an irradiated member such as a bill.
2. Description of the Related Art
Conventionally, an image reading apparatus of this kind is disclosed in, for example, JP-A-2000-113269. Namely, JP-A-2000-113269 discloses a paper currency authenticating apparatus in which a watermark pattern of a paper currency or the like is irradiated with light, the transmitted light is detected by an artificial retina chip, and information such as the shape of an image of the transmissive portion (hereinafter, referred to also as watermark portion) and the presence or absence of the image is processed by a knowledge-processing circuit to authenticate the paper currency. By contrast, JP-A-2003-87564 discloses an image reading apparatus in which so-called transmissive and reflective types are combinedly used. The disclosed image reading apparatus is configured so that a light source for a transmissive original is housed in an original cover, an original mat is detachably engaged with the original cover, the original mat is attached to the original cover when a reflective original is to be read, and the original mat is detached from the original cover when a transmissive original is read.